Most of our efforts have been devoted to continuing our studies on the serological classification of leukemia and lymphoma cells with antisera to normal and leukemia associated membrane antigens. However, new antisera have been elicited to peripheral blood leukemic cells and tissue culture cell lines derived from leukemia and lymphoma patients. Some of the immunizing cells were selected because they lacked Ia antigens as determined by direct testing. The specificity of these antiera is being established by cytotoxicity testing and the nature of the antigens being detected is studied by radiolabelling cell membranes and soluble membrane antigens followed by immuno-precipitation and polyacrylamide gel electrophoresis (RIP-PAGE analysis). In another study, cells from a patient with acute monocytic leukemia and cells from certain patients with acute myelomonocytic leukemia were shown to be good sources of a monokine (lymphocyte activating factor) which causes a blastic response in mouse thymocytes.